In this problem you only need to find the x value of one triangle. If you notice, this is a rectangle that has been cut in half by a diagonal into two equal right triangles. So both the top and bottom part are equal to 500 and both have an angle equal to 10 degrees.
Now looking at the problem, you would have to use tangent since 500 is adjacent and your X value is opposite.
Tan(10) = (X/500)
Now solve by multiplying each side by 500
X= Tan(10) 500 put this in a calculator
Answer is 88.2 degrees